1. Field of the Invention
The present invention relates in general to a direct coupling clutch for a fluid coupling and especially to a diect coupling clutch for automotive transmission hydraulic torque converters operative to transmit torque in a fluid drive relationship from the output shaft of a vehicle engine to the input shaft of a transmission mechanism through a contained fluid interposed between an input element drivingly engaged to the engine output shaft and an output element operatively connected to the transmission input shaft. This invention is more particularly directed to such a clutch which comprises apiston member adapted to frictionally engage with the input element and a damper device consisting of a drive plate to drivingly integrate with the piston member and a driven plate to drivingly connect with the drive plate through resilient torsional force absorbing means such as coil springs arranged in the driven plate.
2. Description of the Prior Art
In the prior art, there have been proposed various dampers for hydraulic torque converter clutches for damping the torsional vibrations delivered from vehicle engines to transmission mechanisms at the lockup of the torque converter. In a most typical example, the damper consists in the main of a driven plate designed to drivingly engage with the transmission mechanism input shaft and carrying thereon a row of coil springs, normally in groups differing in spring characteristic from each other, located adjacent to its external periphery, arranged in circumferentially spaced apart relationship, and a drive plate disposed opposite to the driven plate and designed to drivingly engage with the engine output shaft through a piston member. The drive plate has a row of circumferentially spaced windows cut adjacent to its external periphery, so located and dimensioned that the springs installed in the driven plate are individually fitted into the windows. With this arrangement, when the torque converter is locked up, the torsional forces developed in the drive plate through the engine crankshaft are absorbed by the springs being compressed against the proper edge of their respective window.
With the development of high output engines in these recent years, dampers are more and more required to cope with the greater range of torsional vibratory changes in the hydraulic torque converters. However, those prior art dampers have been found disadvantageous in that the absorption of torsional vibrations at the lockup of the converter is limited by rather narrowly bounded capacity of the drive and driven plates to angularly displace to each other. To solve this problem, a damper employing tvo circumferential rows of resilient members has been proposed. U.S. Pat. Nos. 4,138,003, 4,347,717 and Japanese Laid-open Official Gazette No. 59-195957).
One such example is disclosed in U.S. Pat. No. 4,347,717, in which the damper consists of a drive plate, a driven plate disposed opposite the drive plate, and an intermediate plate interposed between the drive and driven plates. In operation, the drive plate drives through a circumferential row of springs located adjacent to its external periphary the intermediate plate carrying thereon outer and inner concentric circles of springs, the springs in the outer row differing in spring characteristic from the ones in the inner row, such that the torsional vibrations are absorbed by the inner row springs when they are engaged with the driven plate.
Another similar development has been proposed in U.S. Pat. No. 4,138,003, in which the output shaft of the fluid torque converter includes two driven plates carrying thereon two circumferential rows of springs. Two separate direct coupling clutch means are employed to transmit the torque delivered to the piston through the springs in the two rows respectively. Also, separate drive plates are installed for the two driven plates.
Thus, those conventional dampers exemplified by the above two teachings have not been widely acceptable because of the increased nember of components and, particularly in the latter case, the complexity of construction.